Im going to go look at a used 500g acrylic tank. now i know acrylic is different than glass in that it is "welded" instead of silicone which can dry and rot. so what should i check for when i go look at it? the obvious stuff like major scratches and spider cracks, any type of bowing, but is there more i should look for? i just watched the video of a 1500g popping and i dont want this to happen to me. any advice is greatly appreciated!